Function testing method and calibration method for an ophthalmological laser therapy device

Abstract

The present invention relates to a function testing method for a laser apparatus (110) of an ophthalmological laser therapy device (100). The problem is solved by a method which comprises: providing (F1, K3) test signals which represent a plurality of spaced-apart laser pulses of the laser apparatus (110) in an operating region (160, 260) within a test volume (150, 250) comprising hyaluronic acid, acquiring (F2, K4) a spatially resolved data set for detecting an interaction between the laser pulses and the test volume (150, 250), and performing a spatially resolved check (F3, K5) of the data set for interaction. The problem is also solved by a corresponding calibration method, a calibration unit (K), an ophthalmological laser therapy device (100), a computer program product and by a corresponding checking apparatus (200).

Description

[0001] Procedures for functional testing and calibration of an ophthalmic laser therapy device

[0002] The present invention relates to a method for functionally testing a laser device and a calibration method for generating calibration data for a laser device of an ophthalmic laser therapy device. The invention further relates to a corresponding calibration unit, an ophthalmic laser therapy device, a computer program product with program code, and a test device.

[0003] Refractive errors of the human eye have long been corrected with lenses in the form of eyeglasses. However, for some years now, various approaches have been developed to correct refractive errors by modifying the cornea. This modification alters the curvature of the cornea and thus the refractive power of the eye. This is typically achieved by removing tissue from the cornea. By removing corneal tissue, the refractive power of the cornea is altered in such a way that—taking into account the overall optical properties of the eye—the refractive error is reduced or even completely corrected (see, for example, US 6110166 A).

[0004] Carl Zeiss Meditec AG has developed a particularly gentle corneal modification procedure called SMILE. In this procedure, a femtosecond laser is used to create large incisions in the cornea, enclosing a lenticule-shaped piece of corneal tissue. This lenticule is then removed from the cornea through a small access incision. This alters the curvature of the anterior surface of the cornea (the interface between the cornea and air). This change in curvature alters the cornea's refractive power, thereby correcting refractive errors.

[0005] To create the large incisions in the cornea, laser radiation is focused within the tissue—that is, below the tissue surface—to create optical breakthroughs. Various processes, initiated by the laser radiation, occur sequentially within the tissue. If the power density of the radiation exceeds a threshold, an optical breakthrough occurs, generating a plasma bubble within the material. This plasma bubble grows after the optical breakthrough due to expanding gases (in a cavitation bubble). If the optical breakthrough is not maintained, the gas generated in the plasma bubble is absorbed by the surrounding material, and the bubble disappears. However, this process takes much longer than the formation of the bubble itself. When a plasma bubble separates previously fused layers of material, this is usually referred to as photodisruption.For the sake of simplicity, the processes mentioned are summarized here under the term optical breakthrough (or breakthrough), meaning that this term includes not only the actual optical breakthrough but also the resulting effects in the material. If a large number of optical breakthroughs are created next to each other in the fabric, a planar cut (cut surface) can be produced in this way.

[0006] In laser-assisted refractive correction, the laser energy delivered to the eye during treatment should be kept as low as possible, while still exceeding a disruption threshold to ensure that an optical breakthrough can be achieved. Besides the laser energy level, the focusing of the laser beam is crucial for generating an optical breakthrough. This follows from the physical properties of the corneal tissue (such as its band gap) and the wavelength of the femtosecond laser: An optical breakthrough only occurs if the conditions for multiphoton absorption are met. For example, at a laser wavelength of approximately 1000 nm, this requires a high probability of at least four photons being absorbed. The probability P MP applies: Here, #p describe the number of photons, V P the volume of the focus and tP the pulse duration. From this, it follows that both the laser energy (via #p) and the focus quality (V) P ) as well as the pulse duration (t P ) influence whether an optical breakthrough is achieved.

[0007] To verify the functionality of the laser device of an ophthalmic laser therapy device, enucleated pig eyes are currently used because pig eyes are similar to the human eye in terms of geometry, structure, and the biomechanical properties of their components. The pig eye is positioned in front of the laser therapy device (in the position where a human eye would be during laser eye surgery), and the laser device emits laser pulses into the cornea of ​​the pig eye. Subsequently, it is visually (subjectively) checked whether an optical breakthrough has occurred. For this purpose, a cross-section can be created in the cornea of ​​the pig eye. The proportion of the treated area exhibiting a blistering film is then visually (subjectively) assessed.

[0008] The use of enucleated pig eyes has several disadvantages: Firstly, there is a risk of infection for the person performing the functional test; adhering to the necessary hygiene regulations is time-consuming and costly. Secondly, pig eyes can only be used for functional testing for approximately two days after removal, as the tissue changes—despite refrigeration—to such an extent that its use does not yield reliable results. Furthermore, the logistical effort must be considered. In addition, pig eyes are not always available, so there is a risk of supply disruptions. Since pig eyes are biological tissue, consistent quality cannot be guaranteed, meaning that functional testing of the laser device or even calibration of the laser power is prone to errors.Finally, there are ethical or religious aspects that argue against the use of enucleated pig eyes. 2024P00288WG 4.

[0009] The object of the present invention is therefore to provide a method for functional testing of a laser device of an ophthalmological laser therapy device, a calibration method for generating calibration data of a laser device of an ophthalmological laser therapy device, a calibration unit, an ophthalmological laser therapy device, a computer program product and a test device that overcome the aforementioned disadvantages and enable reproducible, objective and temporally flexible functional testing or calibration.

[0010] According to the invention, the problem is solved by the features of the independent claims. Preferred embodiments and configurations are the subject of the dependent claims.

[0011] A first aspect of the invention relates to a method for functionally testing a laser device of an ophthalmic laser therapy device. An ophthalmic laser therapy device is understood to be a device designed to create optical breakthroughs in a human eye—particularly in its cornea—by means of (pulsed) laser radiation, so that, for example, refractive correction of the eye can be achieved. For this purpose, the laser therapy device includes a laser device. The laser device may be or include a femtosecond laser (fs laser); however, other pulsed infrared lasers are also conceivable.

[0012] The procedure for functional verification comprises the following steps: a) Providing test signals representing a multitude of spaced laser pulses from the laser device into a working area within a test volume containing hyaluronic acid.

[0013] The signals can be provided via an interface through which they are made available to the laser therapy device. The laser therapy device can have a control unit that receives the test signals via the interface, converts them into control signals, and forwards them to the laser device. When the test signals are executed, the laser device is controlled to emit a large number of laser pulses. A large number of laser pulses is defined as at least 1,000, 10,000, or 100,000.

[0014] The working area describes the three-dimensional volume into which the laser pulses are delivered. The working area may be predefined by the laser therapy device—for example, by the maximum displacement / deflection into which a laser pulse can be delivered relative to a central position. The working area may have an axial extent (i.e., in a direction along the propagation direction of the laser radiation; e.g., the z-axis) of at least 10 pm, 100 pm, or 500 pm. A maximum axial extent may be 2 mm or 1 mm. The working area may also have a lateral extent (i.e., in directions perpendicular to the propagation direction of the laser radiation; e.g., x-axis, y-axis) of at least 1 mm, 2 mm, or 3 mm. A maximum lateral extent may be 8 mm, 7 mm, or 6 mm. Thus, the laser pulses have a laser focus (or laser spot) located within the test volume.

[0015] Spacing out laser pulses means that the laser pulses are not all emitted to the same location within the working area. There can be at least 5 different locations or at least 50 different locations. The number of (paired) different locations can additionally or alternatively correspond to at least 50%, at least 80%, at least 90%, or at least 98% of the total number of laser pulses.

[0016] According to the invention, the test volume containing the working area contains hyaluronic acid. The molecular formula of the repeating unit of hyaluronic acid is C14H21O11N. b) Acquisition of a spatially resolved data set to detect an interaction between the laser pulses and the test volume.

[0017] Data acquisition can be performed, for example, via an interface. The spatially resolved data set can consist of measurement data from a measuring unit such as a camera or other sensor, whose measurement data allows for the spatially resolved detection of information about the occurrence of an interaction between the laser pulses and the test volume. The detected interaction preferably involves the detection of an optical breakthrough. The plasma bubble associated with the breakthrough and the remaining gas bubble (cavitation bubble) can, for example, be detected optically.

[0018] The acquisition of the spatially resolved data set can be preceded by the transmission of a trigger signal (for example via an interface), which is suitable for initiating the recording of the spatially resolved data set.

[0019] The collected data sets may be measurement data generated, for example, by a measuring unit that is part of the ophthalmic laser therapy device. c) Spatially resolved checking of the data set for interactions.

[0020] The test can be performed on a computer that has a processor and memory. The computer can include at least one processor or processing element, such as a CPU (central processing unit) (optionally in the form of a microprocessor), a GPU (graphics processing unit), a TPU (tensor processing unit), and / or an FPGA (field programmable gate array). The computer can include computer memory, optionally a semiconductor memory chip. The processor can be configured to execute a computer program. The computer program can be stored in the computer memory.

[0021] Testing for the interaction preferably involves detecting optical breakthrough. The result of the test is spatially resolved information about whether an interaction is detectable (or whether and where optical breakthrough could be detected by the multitude of laser pulses).

[0022] The testing can also include providing a test result. This provision can be done via an interface. The described method is based on the inventive finding that the use of a test volume containing hyaluronic acid can overcome the disadvantages of the prior art.

[0023] Hyaluronic acid is a synthetically produced substance (for example, through bacterial fermentation). It is stable (for up to a year or more). This allows for consistent properties as a test material for detecting breakthroughs—unlike pig eyes. Reproducible results can thus be guaranteed. At the same time, hyaluronic acid is transparent (in the visual spectral range as well as for typical wavelengths of a femtosecond laser) and exhibits a viscous consistency, depending on its concentration and intrinsic viscosity. This has proven to be easy to handle, as the test material conforms to the shape of any contact lens used and retains its shape even after docking. Overall, this simplifies the functional verification process compared to the time-consuming process using pig eyes.Furthermore, it was demonstrated that there is a correlation between the interaction of femtosecond laser radiation with hyaluronic acid and the interaction of the radiation with the cornea of ​​the human eye. Specifically, it was shown that at similar laser energies, an optical breakthrough occurs, forming a detectable cavitation bubble. This is because hyaluronic acid has a similar band gap to the cornea of ​​the human eye.

[0024] Acquiring and verifying the data set to demonstrate the interaction also allows for more reliable results than those obtained through visual (subjective) testing. Furthermore, spatially resolved testing enables the detection of any spatial variations in the optical penetrations, which may be caused, for example, by changes in focus quality within the working area. The method according to the invention thus provides a time- and resource-saving method for functionally verifying the laser device of an ophthalmic laser therapy device.

[0025] A second aspect of the invention relates to a calibration method for generating calibration data of a laser device of an ophthalmological laser therapy device.

[0026] The calibration procedure includes the procedural steps for functional verification according to the first aspect described above.

[0027] The calibration procedure further includes the following steps: d) Selecting an initial laser energy Ei.

[0028] The selection can be performed by a person (user) or a program. It can involve choosing from a list of possible laser energies. The selection can be random or according to a predefined logic or algorithm. Preferably, the first laser energy, Ei, is greater than zero.

[0029] The selected laser energy Ei is provided in the process step of supplying the test signals (see step a) of the test procedure). The selected laser energy Ei is part of the test signals. e) Calculation of a laser energy-dependent quality factor for evaluating a spatially resolved distribution of the tested interaction between the laser pulses and the test volume.

[0030] The calculation can be performed on a computer (as described above). The calculation is based on the data set, which has been checked for interactions.

[0031] The quality factor can comprise or consist of one or more numbers. A quality factor value can describe different magnitudes and / or properties of the interaction. For example, it could represent the presence of a breakthrough (yes / no – exemplified by 1 / 0) or the size of a cavitation bubble (diameter or volume). This process step thus provides one or more quality factor values ​​for the laser energy used previously (in step b)) (e.g., the initial laser energy Ei). The quality factor is a measure of the spatially resolved distribution of the tested interaction between the laser pulses and the test volume.

[0032] The quality factor can be defined for each laser pulse of the multitude of laser pulses mentioned in step b) and recorded in step c). Such a quality factor could, for example, be a "map" marking where a breakthrough was detected. Alternatively, the quality factor could be defined for only a fraction of the laser pulses—preferably for at least 10, at least 20, or at least 50 different locations within the working area of ​​the test volume. Such a quality factor could, for example, be a "coarse" map with at least 10 (or 20 or 50) regions, for which a breakthrough was detected is marked as a representative example.

[0033] Additionally or alternatively, the quality can be expressed as a value derived from the entirety or spatially resolved distribution of the tested interaction. Such a quality can, for example, be a number describing the proportion of the multitude of laser pulses for which an interaction (breakthrough) was detected. The "entirety" comprises at least 50% of the multitude of emitted (and tested) laser pulses, preferably at least 80% or 90%.

[0034] Calculating the laser energy-dependent quality can be done using artificial intelligence (Kl). f) Checking (K7) a termination criterion.

[0035] The check can be performed on a computer (as described above). The termination criterion can be for which and / or how many laser energies the laser energy-dependent quality factor has already been calculated. The termination criterion can also be one or more limit values ​​that have been exceeded (or fallen below or reached) by the previously calculated laser energy-dependent quality factor. The termination criterion can also be one or more limit values ​​that are derived (calculated) from the quality factor. g) Select a laser energy Ei that differs from the previously selected laser energies and repeat steps a), b), c), e), and f) if the termination criterion is not met. Here, i > 1.

[0036] The laser energy can be selected from a variety of continuous or discrete values, Ei. The selected laser energy is different from all previously selected laser energies (Ei + Ej with i > 1 for all j < i). An energy difference AE between the selected energy Ei and the immediately preceding energy E can correspond to the minimum energy difference achievable with the laser source of the laser device. Advantageously, the energy difference AE between successively tested laser energies is constant; however, the energy difference AE can also be selected as non-constant.

[0037] When steps a), b), c), e), and f) are repeated, a pattern assigned to the multitude of laser pulses in step a) (using the first laser energy Ei) may exhibit a similar or even identical pattern in the repetition of step a) (using laser energy Ei). The similarity may relate to the spatial extent of the pattern as well as, additionally or alternatively, to the minimum, maximum, and / or mean spacing of the spaced laser pulses. A similar or identical pattern is advantageous for comparing the laser energy-dependent quality factors.

[0038] The selection can be done in a computer (as described above). h) Determining a limiting energy EG of the laser device when the termination criterion is met.

[0039] The determination is based on the laser energy-dependent quality factor for evaluating the spatially resolved distribution of the tested interaction between the laser pulses and the test volume. The limiting energy (LE) describes a laser energy value that ensures optical breakthrough. The limiting energy (LE) can vary spatially, meaning it may have different values ​​for different locations within the test volume.

[0040] Determining the limiting energy EG can be done in a computer (as described above). i) Establishing calibration data for the laser device.

[0041] The setting is based on the previously determined limit energy EG. The limit energy EG defines the lowest value for the laser energy required to perform a continuous, planar incision. From a surgical perspective, however, there are application advantages to using a laser energy that is slightly higher than the limit energy EG. This increased laser energy can be determined by multiplying by a factor (greater than one) or by adding a constant value. This increased laser energy is a value from the calibration data of the laser device.

[0042] In case it is desired to remain below the threshold for a breakthrough, energy can also be subtracted from the marginal energy EG to determine the calibration data, or the marginal energy EG can be multiplied by a factor less than one.

[0043] The calibration data can be set in a computer (as described above). The factor or the constant additive (or subtractive) energy value can be determined empirically. This determination can also be performed using artificial intelligence (AI).

[0044] Preferably, the method also includes the step of providing the calibration data to the ophthalmic laser therapy device. This can be done, for example, via an interface.

[0045] The advantages of the functional testing method described above (first aspect) also apply to the calibration method according to the invention presented here (second aspect).

[0046] In addition, the presented calibration method allows for an objective and reproducible calibration of the laser device, which was not possible with the prior art. According to an advantageous embodiment of the functional testing method and the calibration method, these are characterized in that a test material in the test volume is at least viscous and has a dynamic viscosity of at least 100 mPa / s.

[0047] The test material, which contains hyaluronic acid as described above, fills the test volume; this means that no other material is present in the test volume. In the context of this application, "at least viscous" means that the test material is not liquid. It can therefore be viscous or more solid than viscous—for example, "pudding-like." A dynamic viscosity of 100 mPa / s (millipascals per second) is typically used as the boundary between a liquid and a viscous material.

[0048] The dynamic viscosity is evaluated at the temperature at which the functional test or calibration is to take place. This is typically room temperature.

[0049] Using a test material with at least a high viscosity (containing hyaluronic acid) simplifies handling as described above. Avoiding a liquid test material also prevents gas bubbles, which arise during optical breakthrough, from moving within the material. This allows for the detection of an interaction between a laser pulse and the test volume without immediate detection (e.g., after each individual laser pulse). Instead, the required number of laser pulses can be generated first; subsequently, spatially resolved detection of the interaction is possible without time constraints, and without gas bubbles having diffused into the test volume and distorted the results.

[0050] According to a further advantageous embodiment of the functional testing and calibration methods, these are characterized in that the hyaluronic acid has a concentration of at least 5 mg / ml. Preferably, the concentration is at least 10 mg / ml, at least 20 mg / ml, or at least 30 mg / ml. The concentration is given in milligrams per milliliter.

[0051] It was demonstrated that for these concentrations, both the test material is easy to handle and the detection of an interaction with laser pulses is easily comparable.

[0052] In one embodiment of the method for functional testing and the calibration method, these are characterized in that the hyaluronic acid has a concentration of up to 50 mg / ml, preferably up to 40 mg / ml or up to 35 mg / ml or up to 32 mg / ml.

[0053] Hyaluronic acid can also have a concentration between 5 mg / ml and 50 mg / ml, between 10 mg / ml and 40 mg / ml, between 20 mg / ml and 35 mg / ml, or between 30 mg / ml and 32 mg / ml.

[0054] One example is the product Z-HYALCOAT® from Carl Zeiss Meditec AG. The hyaluronic acid used there has a concentration of 30 mg / ml.

[0055] When hyaluronic acid is used in the aforementioned procedures within the limits mentioned above, both the similarity of the laser energies between the test volume and the human cornea for an optical breakthrough and easy handling due to the viscosity of the material in the test volume are ensured.

[0056] According to one embodiment, the process is characterized in that the hyaluronic acid has an intrinsic viscosity of at least 8 dl / g, preferably at least 10 dl / g. The intrinsic viscosity is given in deciliters per gram.

[0057] Handling is simplified with hyaluronic acid possessing such intrinsic viscosities. Furthermore, unwanted movement of generated gas bubbles in the test material is minimized. 2024P00288WG 14

[0058] According to a further embodiment, the process is characterized in that the hyaluronic acid has an intrinsic viscosity of up to 40 dl / g, preferably up to 20 dl / g, and particularly preferably up to 12 dl / g. Handling is particularly simplified with hyaluronic acid possessing such intrinsic viscosities.

[0059] Hyaluronic acid can also have an intrinsic viscosity between 8 dl / g and 40 dl / g, or between 10 dl / g and 40 dl / g, between 10 dl / g and 20 dl / g, or between 10 dl / g and 12 dl / g. This greatly simplifies handling and reduces the effect of photodisruption-induced bubbles moving within the test material.

[0060] In a further embodiment of the procedure for functional testing and the calibration procedure, these are characterized by the fact that the acquisition of the spatially resolved data set for demonstrating the interaction includes measurement data from reflection imaging (or digital photography).

[0061] In the context of this application, reflection imaging refers to imaging methods that are not based on interference but allow a two-dimensional view (perpendicular to an optical axis of the imaging system) of a sample, where the detected radiation is light reflected from the sample. This can involve a camera whose observation optics are designed to observe the eye—in particular, its cornea. Preferably, the camera also includes illumination that illuminates the eye. The illumination optics and the observation optics may be partially identical.

[0062] Reflectance imaging is particularly suitable for detecting cavitation bubbles by evaluating contrast in the image. It thus enables a highly reliable and reproducible spatially resolved check of the data set for the occurrence of interaction between the laser pulses and the test volume.

[0063] According to one embodiment of the method, the spatially resolved examination of the data set for interaction includes contrast-based image processing. Such processing of the data set is particularly well suited for demonstrating the interaction.

[0064] In one embodiment of the functional testing and calibration methods, these are characterized in that the test signals are provided such that the laser pulses have a minimum distance of no more than 10 pm from each other, preferably no more than 3 pm or no more than 1.5 pm. In other words, the distance of each laser pulse to the nearest neighboring laser pulse is no more than 10 pm, 3 pm, or 1.5 pm.

[0065] Additionally or alternatively, the method is characterized in that adjacent laser pulses have a maximum distance of at most 10 pm, preferably at most 3 pm or at most 1.5 pm. The aforementioned maximum distances apply to at least 50% of the plurality of laser pulses, preferably at least 80% or 95%. In two dimensions, the maximum distance of adjacent laser pulses means that when the area around a laser pulse is divided into four equal segments, the aforementioned maximum distances for a nearest neighbor are maintained in at least two of these equal segments. In three dimensions, the maximum distance of adjacent laser pulses means that when the area around a laser pulse is divided into eight equal solid angles, the aforementioned maximum distances for a nearest neighbor are maintained in at least two of these equal solid angles.

[0066] If test signals are provided as described above, the interaction between the laser pulses and the test volume can be demonstrated particularly well. Furthermore, the distribution (pattern) of the laser spots is similar to patterns that can occur in applications on the human eye, so that function and calibration can be performed not only on the scale of individual breakthroughs, but also on the scale of surgically relevant dimensions.

[0067] According to a further development of the procedure for functional testing and the calibration procedure, these are characterized in that the provision of the test signals is carried out in such a way that the multitude of the defective laser pulses has the shape of an intersection.

[0068] In other words, when the test signals are executed by the laser device of the ophthalmic laser therapy unit, the pattern of cavitation bubbles generated by the numerous laser pulses in the test volume has the shape of a cross-sectional surface. A cross-sectional surface is a collection of laser pulses that forms a two-dimensional surface in three-dimensional space. When a cross-sectional surface is generated in the human eye, it serves to cut tissue; any existing tissue bridges act as "weak points" when the tissue volume is removed.

[0069] The cut surface can correspond to a cap cut in terms of geometry and arrangement of the laser spots. This is a cut surface that, when used in a human eye, is used to delineate a lenticule in the cornea, facing the anterior surface of the cornea. The cut surface can also correspond to a lenticule cut in terms of geometry and arrangement of the laser spots. This is a cut surface that, when used in a human eye, is used to delineate a lenticule in the cornea, facing away from the anterior surface of the cornea.

[0070] If test signals are provided that represent an interface, the procedure for functional testing or calibration reproduces the conditions occurring during application on the human eye particularly well.

[0071] In a further embodiment of the calibration method, it is characterized in that the method additionally comprises receiving a measurement of the actual emitted laser energy for at least one laser pulse of the plurality of laser pulses. Preferably, measurements of the actual emitted laser energies are received for at least 20% of the plurality of laser pulses, and particularly preferably for at least 50% or 80%. The measurement can be received via an interface. To measure the actual laser energy, a (known) fraction of the laser radiation can be coupled out of the beam path and directed onto a measuring device that converts the measurement signal into a measured value for the laser energy.

[0072] The process can include storing the actual laser energy emitted. This storage can be done, for example, in an electronic memory.

[0073] In addition, the calibration procedure is designed in such a way that the determination of the limiting energy EG of the laser device is carried out using the actually emitted laser energy.

[0074] Taking into account the actual emitted laser energy when determining the limiting energy EG improves the robustness of the calibration procedure.

[0075] According to a further development of the calibration procedure, this also includes the acquisition of a spatially resolved reference dataset. This acquisition can be performed via an interface.

[0076] A reference dataset is defined as a dataset acquired in the same manner as a dataset used to detect an interaction between the laser pulses and the test volume. However, unlike the latter, no laser pulses were emitted into the test volume. Alternatively, only laser pulses with a laser energy below a threshold value were emitted into the test volume. This threshold value is set at a maximum of 80% of a previously determined threshold energy (EG), preferably at a maximum of 50% or 20%. No interaction should be detectable in the reference dataset.

[0077] Preferably, the calibration procedure is designed such that the reference data set is taken into account when checking the data set for interaction (process step d)).

[0078] Using the reference dataset can improve the quality of spatially resolved interaction testing, as it reduces the risk of misinterpreting the dataset due to impurities in the test volume, ambient light and / or background disturbances.

[0079] In a further embodiment of the calibration procedure, it is characterized in that, upon selection of the laser energy Ei, an additional working area is selected that differs from the previously selected working areas. Preferably, this additional working area is disjoint from all previously selected working areas. The additional working area can be laterally and / or axially displaced relative to the previously selected working areas. If the additional working area is axially displaced relative to the previously selected working areas, it is preferably located at a smaller distance from an optical aperture through which the laser pulse exits the ophthalmic laser therapy device than the previously selected working areas. In other words, the additional working area is positioned less deeply within the test volume than the previously selected working areas.

[0080] Selecting an additional working area can be achieved by adjusting the test signals to select a different subvolume as the additional working area within the application volume accessible by the ophthalmic laser therapy device. Additionally or alternatively, the test volume can be shifted relative to the ophthalmic laser therapy device. For this purpose, control signals (via an interface) can be provided to actuate an adjustment unit designed to move the test volume relative to the ophthalmic laser therapy device. This adjustment unit could, for example, be a motorized sliding table. Alternatively, a signal (e.g., visual or audible) can be provided indicating that the subvolume should be shifted manually relative to the ophthalmic laser therapy device.

[0081] By selecting a wider working area, it can be advantageously ensured that for each laser energy value (E), a working area within the test volume can be irradiated with laser pulses into which no laser pulses were previously emitted. This prevents cavitation bubbles already present in the working area from distorting the result of an interaction test for the newly selected laser energy value (E).

[0082] According to a further development of the calibration procedure, this is characterized by the fact that after selecting the further working area and before providing test signals for laser pulses with laser energy Ei, a further spatially resolved reference data set is acquired.

[0083] By using the reference dataset for each additional work area, the quality of spatially resolved interaction testing can be improved, as the risk of incorrect interpretation of the dataset due to impurities in the test volume, for example, can be reduced.

[0084] In a further embodiment of the calibration procedure, it is characterized in that the laser energy Ei is selected such that the selected laser energy Ei is greater than all previously selected laser energies Ej. In other words: Ei > Ej with i > 1 for all j < i.

[0085] By selecting increasing laser energy, the quality of spatially resolved interaction testing can be improved, as it is also possible to check the plausibility of interactions occurring in areas of the working area where interactions have already been demonstrated for lower laser energies, and whether these interactions also occur at higher energies.

[0086] Conversely, due to the aforementioned plausibility, the selection of increasing laser energies eliminates the need to choose a new working area for each laser energy. Additionally or alternatively, it is possible to forego providing test signals for areas within the working volume where an interaction has already been detected. Both of these factors contribute to accelerating the calibration process.

[0087] If the laser energy-dependent quality is taken into account when checking the termination criterion, the calibration procedure can also be accelerated by selecting increasing laser energies. According to a further embodiment of the calibration procedure, it is characterized in that the laser energy-dependent quality corresponds to a proportion of the multitude of spaced-apart laser pulses in the test volume for which an interaction is detectable. For example, it can be checked for each laser pulse (or a predefined fraction thereof) whether an interaction has occurred (for example, by checking whether a cavitation bubble can be detected in the spatially resolved data set). The proportion then corresponds to the ratio of the number of laser pulses with detected interaction to all laser pulses tested.Additionally or alternatively, the interaction test can also be performed for several sub-areas (at least 10, 20, or 50) of the work area, for which it is checked whether an interaction is detectable. The proportion then corresponds to the ratio of the number of sub-areas with a detected interaction to all tested sub-areas. Preferably, the sub-areas are all the same size and / or evenly distributed within the work area. The entirety of the sub-areas can correspond to a "map" that represents a spatial distribution of any detected interaction. This map can describe the coverage of the work area with cavitation bubbles.

[0088] If the laser energy-dependent quality factor is calculated as described above, the use of artificial intelligence for the calculation is particularly suitable. Furthermore, contrast-based image processing is also particularly well-suited for determining the laser energy-dependent quality factor, either additionally or as an alternative.

[0089] Preferably, the calibration procedure is designed such that the termination criterion is met when the proportion of detectable interaction is at least 80%, 90%, 95% or 99%.

[0090] If the laser energy-dependent quality is calculated as described above, a spatially resolved limiting energy EG can be calculated particularly well, or spatially resolved calibration data can be determined. According to one embodiment of the calibration method, this is characterized by the fact that the limiting energy EG is determined using a modified sigmoid function.

[0091] The modified sigmoid function for describing the laser energy-dependent

[0092] Quality can take the following forms:

[0093] These are and c fit parameters. A min and A max describe a minimum and a maximum quality that were calculated for the different laser energies E.

[0094] If the laser energy-dependent quality factor is, for example, the proportion (in percent) of laser pulses for which an interaction is detectable, then in ideal measurements A min = 0 and A max = 100.

[0095] If the function A(E) is inverted (formation of -1 (.) ), it is easy to derive for which laser energies E a given proportion of detectable interaction can be achieved; for example E 5Q = -1 (50%) or E 95 = A" 1 (95%).

[0096] Preferably, the marginal energy EG SO is chosen to correspond to an energy for a quality (or proportion) of at least 80%, preferably at least 90%, 95% or 99%.

[0097] The described use of a modified sigmoid function allows for a particularly robust determination of the limiting energy. Other functions that describe a functional relationship between the laser energy and a component of the detected interaction are also conceivable.

[0098] In a further embodiment of the calibration procedure, it is characterized by the spatially resolved determination of the limiting energy (EG) of the laser device. In other words, different limiting energies (EG) can be determined for different locations among the multitude of laser spots. Due to the properties of the laser device and / or the optical beam paths and / or any scanning device used to shift the laser beam focus within the working area, the laser energy for which an interaction between the laser pulse and the test volume is detectable may vary spatially. Such spatial variation can, for example, provide information about focus quality.

[0099] A spatially resolved limiting energy has the advantage that, when applied to the human eye, only enough laser energy needs to be applied to generate a cavitation bubble at the respective location. The total energy delivered to the eye during laser surgery can thus be reduced.

[0100] For this purpose, the calibration procedure is preferably designed such that the calibration data of the laser device is determined with spatial resolution. The calibration data are therefore preferably determined taking into account the spatially resolved limiting energy EG.

[0101] According to one embodiment of the calibration procedure, it is characterized by the fact that it further includes storing the last spatially resolved data set or all spatially resolved data sets and / or the limit energy EC and / or the calibration data and / or the measurements of the actual laser energy delivered. Furthermore, the procedure can include storing intermediate results or so-called metadata such as a time, a date, or a serial number of the ophthalmic laser therapy device.

[0102] Storing the aforementioned data increases the reproducibility of the results and allows the results to be checked at a later time.

[0103] A third aspect of the invention relates to a calibration unit for an ophthalmic laser therapy device. This unit comprises a computing device configured to perform a calibration procedure according to one of the embodiments mentioned above. The computing device is further configured to receive the spatially resolved data set(s) for detecting an interaction, to provide test signals, and to provide calibration data.

[0104] The computing device may include or consist of a computer with a processor and memory. The computer may include at least one processor or processing element, such as a CPU (optionally in the form of a microprocessor), a GPU, a TPU (and / or an FPGA). The computer may include computer memory, optionally a semiconductor memory chip. The processor may be configured to execute a computer program. The computer program may be stored in the computer memory.

[0105] Furthermore, the calibration unit has a first interface for receiving the spatially resolved data set (or sets) for verifying the interaction and forwarding it to the calculation unit, a second interface for providing the test signals, and a third interface for providing the generated calibration data. Two or three of these interfaces may be identical.

[0106] The calibration unit can be part of the ophthalmic laser therapy device.

[0107] A fourth aspect of the invention relates to an ophthalmic laser therapy device. This device comprises a calibration unit as described above (according to the third aspect). Furthermore, the ophthalmic laser therapy device includes a control unit for controlling the device, the control unit being connected to the calibration unit via the second interface and the third interface for receiving test and calibration data. The calibration unit may also be part of the control unit. The control unit may include or consist of a computer as described above. The control unit is connected to the devices of the ophthalmic laser therapy device described below in order to control them. This is typically done by means of signal data transmitted from the control unit to the various devices via signal / data lines or wirelessly.The signal data is generated in the control unit, taking the calibration data into account.

[0108] The control unit can typically access all controllable devices of the ophthalmic laser therapy device. It can be a single unit or a multi-part unit, and it can communicate with the controllable devices of the ophthalmic laser therapy device via wired or wireless communication channels.

[0109] The ophthalmic laser therapy device further comprises a laser device for providing a laser beam with laser pulses. The laser device is preferably a device that provides laser pulses with a pulse duration of femtoseconds or picoseconds, and whose focused laser beam is capable of penetrating the tissue of a patient's eye by means of optical breakthrough due to non-linear absorption. For this purpose, the laser device may, for example, comprise a femtosecond laser or a picosecond laser.

[0110] A femtosecond laser, for example, has a wavelength in the range of 750 nm to 1100 nm. However, the use of femtosecond lasers at other wavelengths is also conceivable in principle. The pulse duration of a femtosecond or picosecond laser that can be used here can be selected from a pulse duration range of 50 fs to 5 ps. The pulse energy of a femtosecond or picosecond laser that can be used here is advantageously in a pulse energy range of 20 nJ to 2 pJ. A pulse energy of approximately 130 nJ is particularly preferred. Typically, the laser device can provide laser pulses with a laser pulse frequency of up to 50 MHz. However, the laser device can be configured to reduce the laser pulse frequency.

[0111] The ophthalmic laser therapy device further comprises a focusing device for focusing the laser beam at a focus within the working area of ​​the test volume. The focusing device is designed to focus the laser beam in the tissue of a patient's eye as well as in the working area of ​​the test volume, so that an optical breakthrough can be achieved at the focus. The focusing device is preferably designed to take into account the optical properties of the patient's eye (such as the radii of curvature of the optically effective interfaces – for example, at the cornea – or the refractive indices of the tissue through which the laser is irradiated). Furthermore, the focusing device can be designed to create a focus of the laser beam in the tissue of the patient's eye as well as in the working area of ​​the test volume, with a contact lens (contact element) positioned upstream of the patient's eye (or working area) in the beam path.The contact lens is used to fixate a patient's eye. For hygienic reasons, a contact lens can only be used once during therapy. It is conceivable that a contact lens could be reused for functional testing or calibration, and / or that a special contact lens with less stringent requirements could be used. Both approaches allow for cost savings.

[0112] In addition, the ophthalmic laser therapy device includes a scanning device for moving the focus of the laser beam within the working area of ​​the test volume.

[0113] The scanning device of the ophthalmic laser therapy system allows the focus of the laser beam to be shifted or scanned within the tissue of the eye or within the working area of ​​the test volume. Scanning the laser beam should be possible without restriction in all three spatial directions: x, y, z. Accordingly, the scanning device should be designed to perform lateral scans in the x and y directions as well as z-scans along the optical axis of the pulsed laser beam. The scanning device may incorporate galvo scanners and / or MEMS scanners. The scanning device may also be configured to shift a lens – for example, radially and azimuthally.

[0114] Furthermore, the ophthalmic laser therapy device includes a measuring device for acquiring the spatially resolved data set to demonstrate the interaction. The measuring device can be configured to acquire measurement data from optical coherence tomography and / or reflection imaging. For this purpose, the measuring device can, for example, include a camera with camera optics designed to detect light emitted from the working area and convert it into an electrical signal to obtain the spatially resolved data set. The detected light can be, for example, visible light or infrared light. The measuring device can additionally include a light source (such as a lamp, an LED, or a laser) and illumination optics. The illumination optics are designed to direct the light from the light source into the working area. The illumination optics and camera optics can be partially identical.Additionally or alternatively, the illumination optics and / or camera optics can be section by section identical to the optics through which the laser radiation of the laser device is guided to the working area.

[0115] The ophthalmic laser therapy device according to the invention allows the laser device to be calibrated efficiently, resource-savingly, objectively and reproducibly.

[0116] A fifth aspect of the invention relates to a computer program product which, when executed on an ophthalmic laser therapy device as described above, is configured to perform a calibration procedure according to one of the embodiments described above. The computer program product comprises program code that can be loaded into a computer to execute the calibration procedure.

[0117] A fifth aspect of the invention relates to a test device for calibrating a laser device of an ophthalmic laser therapy device. The test device comprises a test volume containing hyaluronic acid. Furthermore, the test device comprises a housing designed to accommodate the test volume. For this purpose, the housing has a base and preferably a lateral boundary. The housing is shaped such that a laser beam emitted by the laser device can be focused into the test volume. For this purpose, the housing may have an opening through which the laser beam can enter the test volume. The opening is designed such that collisions between the housing and the ophthalmic laser therapy device cannot occur when the test device and the laser therapy device are positioned relative to each other such that the focus of the laser beam lies within the test volume.The opening can be large enough to allow a contact element (also called a contact lens), which couples the laser therapy device to the human eye during laser surgery, to be immersed in the test fixture. Preferably, the housing is designed so that the contact element can come into contact with the test volume. The housing can be a flat shell open at the top (towards the contact element). Alternatively, the housing can have a window that is transparent to the radiation from the laser device.

[0118] Furthermore, the housing is shaped in such a way that a measuring beam can leave the test volume to detect an interaction between the laser beam and the test volume. This ensures that a measurement can be performed to verify the interaction. For this purpose, the housing can have an opening through which the measuring beam can leave the test volume to be detected by a measuring device. Alternatively, the housing can have a measuring window that is transparent to a wavelength of the measuring beam and through which the measuring beam can be detected by the measuring device.

[0119] The described test device is particularly well suited for a functional test or a calibration procedure according to one of the described configurations.

[0120] According to an advantageous embodiment of the test device, the test volume (containing the hyaluronic acid) comprises a test material that is at least viscous and has a dynamic viscosity of at least 100 mPa / s.

[0121] In a further advantageous embodiment of the test device, the hyaluronic acid has a concentration of at least 5 mg / ml, preferably at least 10 mg / ml, at least 20 mg / ml or at least 30 mg / ml. Additionally or alternatively, the hyaluronic acid has a concentration of up to 50 mg / ml, preferably up to 40 mg / ml, up to 35 mg / ml or up to 32 mg / ml.

[0122] According to a further advantageous embodiment of the test device, the hyaluronic acid has an intrinsic viscosity of at least 8 dl / g, preferably at least 10 dl / g. Additionally or alternatively, the hyaluronic acid has an intrinsic viscosity of up to 40 dl / g, preferably up to 20 dl / g, particularly preferably up to 12 dl / g.

[0123] In an advantageous embodiment of the test device, the test volume containing the hyaluronic acid is shaped in such a way that a surface through which the laser beam emitted by the laser device can penetrate into the test volume is convexly shaped.

[0124] When using such a test device with an ophthalmic laser therapy device that uses a contact lens, bringing the contact lens into contact with the test volume is simplified, as the probability of air inclusions occurring is reduced.

[0125] According to an advantageous further development, the surface of the test volume has a smaller radius of curvature than the contact glass in the area where the test volume is to come into contact with the contact glass. In this way, the probability of air inclusions occurring when using a curved contact glass can be further reduced.

[0126] According to one embodiment, the test device is characterized in that the base has a barrier layer, wherein the barrier layer is configured to block the wavelength of the measuring beam and / or visible light, and wherein the barrier layer is in contact with the test volume. To block the measuring beam and / or visible light, the barrier layer can have a transmission of at most 1%, preferably at most 0.01%, 0.0001%, or 0.000001%. Additionally, to block the measuring beam and / or visible light, the barrier layer can have a reflection of at most 10%, preferably at most 1%, 0.1%, or 0.01%. The barrier layer can be configured as a neutral density filter (also called an ND filter or 2024P00288WG 29 in English) and have values ​​such as ND = 2, ND = 4, ND = 6, or ND = 8 (or higher).

[0127] By using a barrier layer as described above, the proportion of detected light from outside the test volume is reduced, so that the measuring beam carries largely only information about the interaction. In this way, the detection of interactions can be carried out with particular reliability. This is especially true for detection using contrast-based image processing.

[0128] A barrier layer for visible light simplifies a visual inspection to determine whether an interaction of the laser radiation with the test volume has occurred.

[0129] In a further embodiment, the test device is characterized in that the lateral boundary has a first and a second lateral access through which the test volume can be inserted into or removed from the housing.

[0130] A test device designed in this way allows the test device and laser therapy device to be aligned once for a functional test or calibration. Between individual measurements to demonstrate the interaction for different laser energies, the test volume can be exchanged via the two lateral access points. This can be done automatically, for example. In this way, the test device enables particularly convenient testing or calibration.

[0131] According to a further embodiment, the test device is characterized in that the housing is designed to be connected to a contact element. The connection can be achieved, for example, by means of a thread, a clamp (such as a bead), or a clamp. Alternatively, the housing has a contact element. Both variants simplify handling during functional testing or calibration of an ophthalmic laser therapy device that uses a contact element during operation (during a laser surgical procedure). This embodiment is particularly advantageous if the lateral edge has two lateral access points, as described above.

[0132] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations given, but also in other combinations or on their own, without leaving the scope of the present invention.

[0133] The invention is explained in more detail below with reference to exemplary embodiments and illustrations, which also disclose essential features of the invention. The exemplary embodiments serve for illustration purposes and are not to be interpreted as limiting. Unless otherwise stated, elements or components from different exemplary embodiments may be combined. If variations or modifications are given for one exemplary embodiment, they may also be applicable to other exemplary embodiments. To avoid repetition, identical or corresponding elements in different figures are marked with the same reference numerals and are not explained multiple times. The figures show:

[0134] - Fig. 1 shows a schematic of an embodiment of an ophthalmic laser therapy device according to the invention;

[0135] - Fig. 2 shows an example of a method for functional testing of a laser device of an ophthalmic laser therapy device;

[0136] - Fig. 3 shows an example of a calibration procedure for generating calibration data for a laser device of an ophthalmic laser therapy device;

[0137] - Fig. 4 Measurements obtained during a calibration procedure;

[0138] - Fig. 5 Measurements for different laser energies, which were calculated to obtain spatially resolved limiting energies;

[0139] - Fig. 6 shows a section through a test device according to a first embodiment;

[0140] - Fig. 7 shows a section through a test device according to a second embodiment; - Fig. 8 shows a section through the test device according to the second embodiment and a contact element of a laser device;

[0141] - Fig. 9 shows a section through a test device according to a third embodiment;

[0142] - Fig. 10 shows a section through a test device according to a fourth embodiment.

[0143] Figure 1 schematically illustrates an embodiment of an ophthalmic laser therapy device 100 (enclosed by a dashed box). During operation of the ophthalmic laser therapy device 100, a laser device 110 emits a pulsed laser beam 115. The laser beam 115 is deflected axially (in the z-direction) by a scanning device 130 and laterally (in the x- and y-directions) by another scanning device 135. A focusing device 120 concentrates the pulsed laser beam 115 into a focus 125 (when the laser therapy device 100 is used to correct the refraction of a human eye) in the cornea of ​​the eye being corrected. Any advantageous fixation of the eye relative to the ophthalmic laser therapy device 100 by means of a contact element is not shown.

[0144] In Fig. 1, the laser beam 115 is directed by the focusing device 120 into a test device 190, which is not part of the laser therapy device 100. The test device 190 comprises a test volume 150 containing hyaluronic acid. Within the test volume 150, a working area 160 is schematically marked by dotted lines. The focus 125 of the laser beam 115 is located within the working area 160. The ophthalmic laser therapy device 100 is designed to move the focus 125 within the working area 160. This is made possible by the scanning devices 130 and 135.

[0145] During operation, the laser device 110 and the scanning devices 130 and 135 are controlled fully automatically via signal data transmitted from a control unit 140 to the respective devices 110, 130, and 135. This is indicated by arrows pointing from the control unit 140 to the devices 110, 130, and 135, respectively. The control unit 140 ensures appropriately synchronized operation of the laser device 110 and the three-dimensional scanning devices 130 and 135. The focusing device 120 could also be controlled by the control unit 140. The signal data can be transmitted via signal data lines or wirelessly. The signal data required for operation is determined in the control unit 140 based on control data.

[0146] During a functional test or calibration of the laser device 110, the control unit 140 receives test signals and, if applicable, calibration data from a calibration unit K via unspecified communication channels, such as a calibration data line (shown in Fig. 1 as a solid line between the calibration unit K and the control unit 140). The transmission of calibration data can also be carried out using memory chips (e.g., via USB or memory stick), magnetic storage media (e.g., floppy disks), wirelessly via radio (e.g., WLAN, UMTS, Bluetooth), or via wired connections (e.g., USB, FireWire, RS232, CAN bus, Ethernet, etc.). As an alternative to direct communication, it is also possible to arrange the calibration unit K spatially separate from the control unit 140 and provide a corresponding data transmission channel.

[0147] The calibration unit K comprises a computing unit C, which is a computer with a processor and memory. Furthermore, the calibration unit K has a second interface S2 and a third interface S3, via which test signals and calibration data can be provided to the control unit 140. In the present embodiment, the second and third interfaces are identical.

[0148] Furthermore, the calibration unit K has a first interface S1 via which a spatially resolved data set for detecting an interaction in the working area 160 between the laser pulses of the laser beam 115 of the laser device 110 and the test volume 150 can be received. In the illustrated embodiment, the spatially resolved data set is provided by a measuring device M. In this example, this is a camera with camera optics that view the working area 160 in the test volume 150 of the test device 190 in the direction (coaxially) of the incident laser beam. The capability of the measuring device M to acquire measurement data (as a spatially resolved data set) is represented in Fig. 1 by a dashed double arrow. A light source, which is also present, is not shown.

[0149] The calculation unit C of the calibration unit K is designed to generate and provide test signals, acquire spatially resolved data sets, and perform spatially resolved interaction checks. The interaction is checked using a contrast-based method. Additionally, the calculation unit C can calculate a laser energy-dependent quality factor to evaluate the spatially resolved distribution of the tested interaction and can also check a termination criterion.

[0150] If the termination criterion is not met, the computational unit C selects a laser energy Ei that differs from all other laser energies already used. Furthermore, the steps of providing test signals, acquiring a spatially resolved data set (for the last selected laser energy Ei), checking for an interaction, and checking a termination criterion are repeated.

[0151] If the termination criterion is met, the calculation device C is set up to determine a marginal energy EG ZU, as well as to define calibration data and provide this via the third interface S3.

[0152] The calibration unit K additionally features an input device (not shown) that is connected to the calculation unit C. An initial laser energy Ei can be input via this device.

[0153] The calibration unit K does not have to be part of the ophthalmic laser therapy device. Alternatively, it can be a separate unit that can be connected to the laser therapy device via the interfaces mentioned. The calibration unit K can have a measuring device; it can also be additionally or alternatively connected via interface S1 to a measuring device that is neither part of the calibration unit K nor of the laser therapy device.

[0154] Figure 2 schematically illustrates a method for functionally testing a laser device of an ophthalmic laser therapy device. The individual method steps are shown schematically in the blocks labeled F1 to F3.

[0155] Process step F1 involves providing test signals representing a multitude of spaced laser pulses from the laser device within a working area contained in a test volume filled with hyaluronic acid. These test signals are then provided to the ophthalmic laser therapy device whose laser mechanism is undergoing functional testing. There, the test signals can be converted (for example, by a control unit) into control signals that trigger execution. During execution, the multitude of laser pulses is generated, corresponding to a multitude of spaced laser foci within the working area of ​​the test volume.

[0156] Process step F2 is performed after the emission of the numerous laser pulses. Here, a spatially resolved data set is acquired to detect an interaction between the laser pulses and the test volume. A corresponding data set is generated after the laser pulses are emitted (e.g., by a measuring unit) and made available to the process.

[0157] Procedure step F3 is performed after procedure step F2. In step F3, a spatially resolved check of the data set for interactions is carried out. In the functional verification procedure shown here, check F3 also includes providing the result of the check.

[0158] The procedure shown in Fig. 2 can be carried out in the calibration unit K shown in Fig. 1. In this case, the test result is made available to the control unit 140 via interface S2 / S3 (2024P00288WQ 35). The control unit 140 is then configured to perform various actions based on the test result, such as issuing a warning if the test result was negative.

[0159] Figure 3 schematically illustrates an example of a calibration procedure for generating calibration data for a laser device of an ophthalmic laser therapy device. The individual procedure steps are schematically depicted in the blocks labeled K1 to K13. The sequence of steps is indicated by the arrows connecting the blocks.

[0160] In process step K1, a spatially resolved reference data set is acquired. In the present calibration procedure, no laser pulses are emitted into the working area before acquisition. However, laser pulses could also be emitted beforehand, preferably well below an expected limiting energy EG.

[0161] K1 is an optional procedure step that allows the quality of spatially resolved interaction testing to be improved in step K5, as the risk of incorrect interpretation of the data set due to impurities in the test volume, ambient light and / or background disturbances of the test volume can be reduced by taking the reference data set into account when testing the interaction.

[0162] Procedure step K2 involves selecting an initial laser energy Ei. In the calibration procedure shown here, this laser energy is significantly below an expected limiting energy EG – for example, 20% to 30% of the expected (e.g., previously determined) limiting energy EG. However, the choice could also deviate from this.

[0163] In process step K3, test signals are provided that represent a multitude of spaced-apart laser pulses from the laser device into a working area within a test volume containing hyaluronic acid. This step corresponds to step F1 in the process shown in Fig. 2. The provided test signals also include information about the selected laser energy. For the first iteration of the loop, this is the first laser energy Ei; in subsequent iterations, it is the laser energy Ei selected in each step K8.

[0164] Process step K4 comprises acquiring a spatially resolved data set to detect an interaction between the laser pulses and the test volume. This step corresponds to step F2 in the process shown in Fig. 2.

[0165] In process step K5, the data set is checked for interactions with spatial resolution. This step corresponds to step F3 in the process shown in Fig. 2.

[0166] In process step K6, a laser energy-dependent quality factor is calculated to evaluate a spatially resolved distribution of the tested interaction between the laser pulses and the test volume.

[0167] Process step K7 involves checking a termination criterion. If the termination criterion is not met, process step K8 follows, which includes selecting a laser energy Ei that differs from the previously selected laser energies. Subsequently, process step K13 is executed, which involves reacquiring a spatially resolved reference dataset. Step K13 is advantageous if, in selecting the laser energy Ei in step K7, an additional working area is also selected that differs from the previously selected working areas. Process step K13 is optional. The process then continues with step K3.

[0168] If the termination criterion is met, process step K9 follows, which involves determining a limiting energy (LE) of the laser device. This is followed by process step K10, which involves defining calibration data for the laser device. In process step K11, the last spatially resolved data set or all spatially resolved data sets and / or the limiting energy (LE) and / or the calibration data and / or the measurements of the actual emitted laser energy are stored. This process step is not mandatory for the calibration procedure, but it improves the reproducibility of the calibration.

[0169] In process step K12, the calibration data is provided.

[0170] The method according to the invention thus enables a time- and resource-saving method for calibrating the laser device of an ophthalmic laser therapy device. The method is objective and reproducible.

[0171] Figure 4 shows measurements obtained during a calibration procedure according to the invention. The first row (row a)) schematically shows, in a cross-sectional plane, where the foci of the plurality of laser pulses were placed within the test volume. The lower, hemispherical element represents the test volume. Above it, a contact element is shown with thicker lines. In this example, the contact element and the test volume are in direct contact.

[0172] The second line (line b)) shows measurement data from a camera. The camera records measurement data along the optical axis of the pulsed laser beam; this corresponds to a top view of the working area. The measurement data was recorded after the laser pulses were emitted into the working area of ​​the test volume. These correspond to the spatially resolved data sets for different laser energies. The measurements show an increased signal at locations where cavitation bubbles were created by the reader pulses, which appears as a lighter gray in line b) of Fig. 4. Locations without cavitation bubbles show a weak signal (or no signal) and remain dark gray. The circular structure in all five camera images shows the outer boundary of the contact element used in the calibration procedure. The third line (line c)) shows an evaluation of the camera measurement data shown in line b).The individual images from row b) were subjected to contrast-based image processing. In each image, wherever the contrast was increased due to the generated bubbles, the corresponding location in the image was marked white. Locations without bubbles, on the other hand, exhibit low contrast against the background and are marked black in the image.

[0173] The first column (marked "E = 0") contains data acquired as a reference. The laser energy was set to zero (E = 0). No cavitation bubbles are visible in the spatially resolved dataset (row c). This is the spatially resolved reference dataset.

[0174] The following columns show data obtained for laser energies other than zero. The second column corresponds to a first laser energy Ei; the last column to a final laser energy E. nDuring the calibration procedure, data were acquired with increasing laser energy (Ej < Ej+i). Line a) shows that for laser energies Ei to E n The foci of the numerous laser pulses in the test volume describe a curved surface, which is shown as a curved line in the cross-sectional view. In this example, the surface runs parallel to the surface of the contact lens and corresponds to a cap section. The top view of the working area in row c) shows that with increasing laser energy, the proportion of locations where cavitation bubbles are visible also increases. The last column shows the last laser energy E. n The area of ​​the cap cut is almost entirely white.

[0175] Fig. 4 shows an example with one reference measurement (reference dataset) and four measurements with different laser energies. The available number of iterations and measurements may be sufficient to determine a limiting energy (EG) that is not spatially resolved. In this case, for example, the quality factor for the different laser energies can be determined by the proportion of detectable interaction—that is, what percentage of the cross-sectional area is shown as whitish in the measurements shown in row c). 2024P00288WQ 39

[0176] For the data shown in line c), values ​​of approximately 0% (for the reference measurement with E = 0), approximately 15%, approximately 45%, approximately 80% and approximately 95% (for the measurement with laser energy E) are obtained. n ).

[0177] If a spatially resolved calibration is desired, the limiting energies must be determined with spatial resolution. For this purpose, a higher number of iterations is recommended to incorporate measurement data from more laser energies into the calibration. Figure 5 shows how measurements from a series of spatially resolved datasets (four measurements are shown as examples on the left in Figure 5) were combined (long arrow on the left) and processed to obtain a spatially resolved distribution of the limiting energies (large arrow in the middle of the figure). The result is shown on the right. The different shades of gray represent different limiting energies. Different limiting energies can occur, for example, if the focus quality varies spatially. In the example shown, the limiting energies are used to calculate spatially resolved calibration data for the laser device.

[0178] Figure 6 shows a section through a test device according to a first embodiment. The test device 200 has a housing 210 with a base 215. The base 215 comprises a barrier layer 240, which is shown in black in Figure 6. In the example shown, this is an ND filter with ND > 6. A test volume 250, shown as a dotted line, is located on the base 215 and in direct contact with the barrier layer 240. The test volume 250 contains hyaluronic acid. In the example shown, this is present at a concentration of 31 mg / ml and has an intrinsic viscosity of approximately 11 dl / g. In the embodiment shown, the laser radiation from the laser device, whose function is to be tested or calibrated, can penetrate the test volume 250 from above. Measurement radiation leaving the test volume 250 to detect an interaction can also be emitted upwards.The use of a barrier layer 240 (which is not strictly necessary) improves the quality of the spatially resolved data set (the measurement data) and thus simplifies the verification of the quality of 2024P00288WG 40. The measurements shown in Figs. 4 and 5 were carried out with a test device according to this embodiment.

[0179] Figure 7 shows a section through a test device according to a second embodiment. In addition to the features shown in Figure 6, the housing 210 in this embodiment has a lateral edge 220. Such an edge 220 can simplify the handling of the test device 200, for example, if the test volume 250 is to have a greater thickness than in the first embodiment (according to Figure 6).

[0180] Figure 8 shows a section through a test device according to the second embodiment and a contact element of a laser device. If the ophthalmic laser device has a contact element 290 (shown with oblique hatching) to fix the patient's eye during laser surgery, the contact element 290 is in direct contact with the eye. Therefore, it is advantageous if a functional test or calibration is also carried out in such a way that the contact element 290 is in direct contact with the test volume 250 – as shown in Figure 8.

[0181] Figure 8 additionally shows a working area 260 and a further working area 206.i (outlined with dotted lines and filled with white). Laser pulses with a first energy Ei can be emitted into the working area. After a measurement (of a first spatially resolved data set), the working area can be shifted so that laser pulses with a laser energy Ei can be emitted into a further working area (260.i).

[0182] It should be noted that the first embodiment according to Fig. 6 is also suitable for use with a laser therapy device with a contact element. This is due to the intrinsic viscosity of the hyaluronic acid.

[0183] Figure 9 shows a section through a test device according to a third embodiment. In addition to the features shown in Figure 7 according to the second embodiment, the boundary 220 here has two lateral access points 260. The test volume 250 can be introduced into the test device via an applicator 270 through the access point 260 shown on the right. The test volume 250 can be removed through the access point 260 shown on the left. The feeding and removal processes are schematically illustrated by corresponding arrows in the lateral access points 260.

[0184] Figure 10 shows a section through a test device according to a fourth embodiment. In addition to the features shown in Figure 9 according to the third embodiment, the housing 210 is designed here to accommodate a contact element 290, which is not part of the test device 200. For this purpose, a continuous bead is provided on the lateral edge 220, by means of which the contact element can be clamped to the test device 200. Other connection options are also conceivable.

[0185] The test device could also be designed such that the contact element is part of the test device. The test device could then be mechanically and optically coupled to the ophthalmic laser therapy device, whose laser mechanism is to be tested, via the contact element.

[0186] The features of the invention mentioned above and described in various embodiments can be used not only in the exemplary combinations given, but also in other combinations or alone, without leaving the scope of the present invention.

[0187] A description of a device relating to process characteristics applies analogously to the corresponding process with respect to these characteristics, while process characteristics represent corresponding functional characteristics of the described device.

Claims

1. 2024P00288WG 42 Patent claims 1. Method for functional testing of a laser device (110) of an ophthalmic laser therapy device (100), comprising: a) providing (F1, K3) test signals representing a plurality of spaced laser pulses of the laser device (110) into a working area (160, 260) within a test volume (150, 250) containing hyaluronic acid, b) acquiring (F2, K4) a spatially resolved data set to detect an interaction between the laser pulses and the test volume (150, 250), c) spatially resolved testing (F3, K5) of the data set for interaction.

2. Calibration method for generating calibration data of a laser device (110) of an ophthalmological Laser therapy device (100), comprising the method according to claim 1, further comprising: d) selecting (K2) a first laser energy Ei, e) calculating (K6) a laser energy-dependent quality factor for evaluating a spatially resolved distribution of the tested interaction between the laser pulses and the test volume (150, 250), f) checking (K7) a termination criterion, g) selecting (K8) a laser energy Ei that is different from the previously selected laser energies, and repeating steps a), b), c), e) and f) if the termination criterion is not met, h) determining (K9) a limit energy EG of the laser device (110) if the termination criterion is met, i) specifying (K10) calibration data of the laser device (110).

3. Method according to claim 1 or 2, characterized in that a test material in the test volume (150, 250) is at least viscous and has a dynamic viscosity of at least 100 mPa / s.

4. Method according to one of the preceding claims, characterized in that the hyaluronic acid has a concentration of at least 5 mg / ml, preferably at least 10 mg / ml, at least 20 mg / ml or at least 30 mg / ml.

5. Method according to one of the preceding claims, characterized in that the hyaluronic acid has a concentration of up to 50 mg / ml, preferably up to 40 mg / ml, up to 35 mg / ml or up to 32 mg / ml.

6. Method according to one of the preceding claims, characterized in that the hyaluronic acid has an intrinsic viscosity of at least 8 dl / g, preferably at least 10 dl / g.

7. Method according to one of the preceding claims, characterized in that the hyaluronic acid has an intrinsic viscosity of up to 40 dl / g, preferably up to 20 dl / g, particularly preferably up to 12 dl / g.

8. Method according to one of the preceding claims, characterized in that the acquisition (F2, K4) of the spatially resolved data set for detecting the interaction comprises data from reflection imaging.

9. Method according to one of the aforementioned claims, characterized in that the spatially resolved checking (F3, K5) of the data set for interaction comprises contrast-based image processing.

10. Method according to one of the preceding claims, characterized in that the provision (F1 , K3) of the test signals is carried out in such a manner, - that the laser pulses have a minimum distance of no more than 10 pm from each other, preferably no more than 3 pm or no more than 1.5 pm, and / or - that adjacent laser pulses have a maximum distance of 10 pm, preferably a maximum of 3 pm or a maximum of 1.5 pm.

11. Method according to one of the preceding claims, characterized in that the provision (F1 , K3) of the test signals is carried out in such a way that the plurality of the rejected laser pulses has the shape of a cross-sectional surface.

12. Calibration method according to one of claims 2 to 11, characterized in that the method further comprises: - Receiving a measurement of actual emitted laser energy for at least one laser pulse of the plurality of laser pulses, - preferably storing the actually emitted laser energy, and - Determining (K9) the limiting energy EG of the laser device (110) using the actual emitted laser energy.

13. Calibration method according to one of claims 2 to 12, characterized in that the method further comprises: - Capture (K1 ) a spatially resolved reference dataset.

14. Calibration method according to one of claims 2 to 13, characterized in that by selecting (K8) the laser energy (Ei) an additional working area (260. i) is selected which is different from the previously selected working areas.

15. Calibration method according to claim 14, characterized in that after selecting the further working range (260. i) and before the 2024P00288WG 45 Providing (K3) test signals for laser pulses with laser energy Ei, and acquiring (K13) another spatially resolved reference data set takes place.

16. Calibration method according to one of claims 2 to 15, characterized in that the selection (K8) of the laser energy (Ei) is carried out such that the selected laser energy (Ei) is greater than all previously selected laser energies Ej.

17. Calibration method according to one of claims 2 to 16, characterized in that the laser energy-dependent quality corresponds to a proportion of the plurality of spaced laser pulses in the test volume (150, 250) for which an interaction is detectable, and preferably that the termination criterion is met when the proportion of detectable interaction is at least 80%, 90%, 95% or 99%.

18. Calibration method according to one of claims 2 and 17, characterized in that the determination (K9) of the limiting energy EG is carried out using a modified sigmoid function or with another function that describes a functional relationship between the laser energy and a proportion of proven interaction.

19. Calibration method according to one of claims 2 to 18, characterized in that the determination (K9) of the limit energy EG of the laser device (110) is spatially resolved, and preferably that the determination (K10) of the calibration data of the laser device (110) is spatially resolved.

20. Calibration method according to one of claims 2 to 19, characterized in that the method further comprises: - Storing (K11 ) the last spatially resolved data set or all spatially resolved data sets and / or the limit energy EC and / or the calibration data and / or the measurements of the actual emitted laser energy.

21. Calibration unit (K) for an ophthalmic laser therapy device (100), comprising - a computing device (C) configured to: o perform a calibration procedure according to one of claims 2 to 20, o receive the spatially resolved data set for detecting an interaction, o provide test signals, and o provide calibration data, - a first interface (S1 ) for receiving the spatially resolved data set to prove the interaction and for forwarding it to the computational unit (C), - a second interface (S2) for providing the test signals, and - a third interface (S3) for providing the generated calibration data.

22. Ophthalmic laser therapy device (100), comprehensive - a calibration unit (K) according to claim 21 , - a control unit (140) for controlling the ophthalmic laser therapy device (100), wherein the control unit (140) is connected to the calibration unit (K) via the second interface (S2) and the third interface (S3) for receiving the test data and the calibration data, - a laser device (110) for providing a laser beam (115), - a focusing device (120) for focusing the laser beam (115) at a focus (125) in the working area (160, 260) of the test volume (150, 250), - a scanning device (130, 135) for moving the focus (125) of the laser beam (115) in the working area (160, 260), and - a measuring device (M) for recording the spatially resolved data set to demonstrate the interaction.

23. Computer program product which, when executed on an ophthalmic laser therapy device (100) according to claim 22, is configured to execute a method according to any one of claims 2 to 20.

24. Test device (190, 200) for calibrating a laser device (110) of an ophthalmic laser therapy device (100), comprising - a test volume (250) containing hyaluronic acid, - a housing (210) designed to accommodate the test volume (250), with a base (215) and preferably with a lateral boundary (220), wherein the housing (210) is shaped such that a laser beam (115) emitted by the laser device (110) can be focused into the test volume (250), and wherein the housing (210) is shaped such that a measuring beam can leave the test volume (250) to detect an interaction between the laser beam and the test volume (250).

25. Test device (190, 200) according to claim 24, characterized in that the test volume (250) has a surface through which the laser beam (115) emitted by the laser device (110) can penetrate into the test volume (250), which is convexly shaped. 2024P00288WG 48 26. Test apparatus (190, 200) according to claim 24 or 25, characterized in that the bottom (215) has a barrier layer (240), wherein the barrier layer (240) is configured to block the wavelength of the measuring beam and / or to block visible light, and wherein the barrier layer (240) is in contact with the test volume (240).

27. Test device (190, 200) according to one of claims 24 to 26, characterized in that the lateral boundary (220) has a first and a second lateral access (260) through which the test volume (250) can be inserted into or removed from the housing (210).

28. Test device (190, 200) according to one of claims 24 to 27, characterized in that the housing (210) is designed to be connected to a contact element (290), or that the housing (210) has a contact element (290).

Images